Women who start the menopause earlier have a greater risk of being taken to hospital with heart failure, researchers have found.

The US-based study also revealed that women who have never given birth have more than a two-fold increase in the risk of a common type of the condition, known as diastolic heart failure, compared with women who have children.

The authors say the new study flags up the importance of looking at how factors such as pregnancy and reproductive period are related to cardiovascular health. “Those are actually factors that can influence a woman’s risk of cardiovascular disease, including congestive heart failure,” said Nisha Parikh, co-author of the research from the University of California, San Francisco.

Writing in the Journal of the American College of Cardiology, Parikh and colleagues from seven US institutions describe how they analysed data from 28,516 women to explore the link between heart failure and various reproductive factors.

The data was collected through a US study known as the Women’s Health Initiative, with the women beginning the study between 1993 and 1998, with an average age of just under 63 years. The average age of menopause was 47 years and the women were followed up for an average of just over 13 years. Overall, 1,494 of the participants were taken to hospital with heart failure.

Once a host of factors including age, education level, smoking, body mass index, use of oral contraceptives and hysterectomy were taken into account, the team found that earlier onset of menopause – and hence a shorter reproductive duration – was linked to an increased risk of heart failure.

For every year later that a woman experienced menopause, the team found that she had a 1% decrease in the risk of heart failure. Further analysis revealed that the link appears to be concentrated among women who began the menopause naturally, rather than as a result of surgical procedures.

While the study does not explore the reasons behind the link, the authors note that previous research has suggested the increased cardiovascular health disease risk with early menopause could, in part, be related to lower lifetime exposure to sex hormones such as oestrogen.

The latest study also found that women who had never given birth were 2.75 times more likely to have diastolic heart failure than women who had children.

While the researchers found no sign that infertility was behind the increased risk, Parikh said that association cannot be ruled out. Conditions such as polycystic ovary syndrome that can lead to infertility, she notes, have also been linked to an increased risk of cardiovascular disease. It is also unclear whether those who experienced infertility had unsuccessful fertility therapy. But, adds Parikh, a number of other factors may also be contributing to the link.

“It could be lifestyle factors at play, certainly you could hypothesise that there could be factors like depression that might underlie the association in some women,” said Parikh. “Of course, many women choose not to get pregnant and we don’t know what could be at play there as well.”

The team note that the study did not explore the influence of pregnancy complications, such as pre-eclampsia and pregnancy-related high blood pressure, on the risk of heart failure.

Parikh said she hoped the study would raise awareness of the link between reproductive factors and cardiovascular conditions, and added that doctors should be aware of such associations when considering a woman’s risk of heart failure.

“We already know that early menopause may increase a person’s risk of developing other forms of cardiovascular disease, probably through reduced lifetime exposure to the sex hormone oestrogen,” he said. “Now, this study suggests that early-onset menopause may also be associated with an increased risk of developing heart failure.”

But Avkiran stressed that it is not yet clear how oestrogen protects the heart. “Hormone replacement treatment has not been consistently shown to reduce the risk of cardiovascular disease in post-menopausal women, so women considering such treatment should discuss its potential benefits and risks with their doctor,” he said.

Henry Boardman, of the cardiovascular clinical research facility at the University of Oxford, noted that the study only showed associations, not causation.

He also added that the finding that not having children is associated with an increased risk of heart failure should be treated with caution, given that it is based on findings from a small number of women, and only one type of heart failure.

But while Boardman notes that the absolute risk of heart failure is small he said the study emphasises that women’s pregnancy and reproductive health is relevant to cardiovascular health.

“Women whom have premature menopause should have a conversation with their GP about this and their other cardiovascular risk factors,” he said. “However, I do not think women should plan the timing or the size of their families based on how it might affect their hearts.”